Electrical circuits such as wafers or printed circuit boards are electrically or functionality tested by various existing industrial equipment that uses probes that contact dedicated contact elements such as bond-pads or bumps. A probe card includes many probes, which can be arranged with various layouts. A probe card can be shaped such as to contact one or more groups of bond-pads or bumps at a time.
The probe is usually made of a very tough material and its end (its tip) is very small. Bond pads or bumps are usually much larger and are made of less durable materials. When a probe contacts a bond pad or a bump it can deform the bond-pad or bump. This deformation is known as a probe mark. Some probe marks can render the wafer inoperative. In some cases the probe can pass through the bond pad and expose inner portions of underlying material.
FIG. 1 illustrates a prior art image of multiple bumps (such as bump 92) and probe marks (such as probe mark 90). FIG. 2 illustrates a prior art bond pad 94 with a probe mark 96.
After the electrical or functional test ends the electrical circuits and especially their bond pads or bumps are optically inspected.
Various foreign particles, corrosion, foreign material as well as various artifacts (hereinafter—artifacts) can resemble probe marks. In many cases automatic inspection systems can identify these artifacts as probe marks. This erroneous identification can cause functional dice to be defined as non-functional dice and is very costly.
There is a growing need to provide efficient systems and methods for evaluating contact elements.